How to create a realistic shader for french fries?
The method I'd prefer for realism is microdisplacement.  Set your Cycles feature set to experimental so that you can use the Adaptive feature of the Subdivision Surface modifier.


And then set up your material for displacement and bump so that when you connect something to the displacement socket it modifies the mesh.

I used the same Noise Texture for both the Base Color and Displacement, so that I could make the areas with the most displacement a more golden brown.  The Scale values have to be adjusted for the scale you're working at.

I found that a Midlevel of 0 did some work to kind of puff up the model as though it had actually been deep fried, which was kind of fun.
Subsurface Radius value was 1, 1, 1 for this shot.
If that doesn't suit, or if a bunch of highly subdivided shapes are going to be too heavy for the final scene, I think it looks ok with Bump Only, you'd just have to do some work with the model to avoid it looking flat.  It looks like you have some pretty good shape variations to work with so maybe that's a place to start.